Drawing board attachment



June 30, 1931. c. A. GREEN 1,312,477

DRAWING BOARD ATTACHMENT Filed April 9. 1927 2 Sheets-Sheet l 25 v nuentop J2 6.72 72 V 'l' June 30, 1931. c. A. GREEN 1,812,477

DRAWING BOARD ATTACHMENT Filed April 9. 1927 2 Sheets$heet 2 J's 24r Fatentecl June 30, 1931 UNITED STATES PATENT OFFICE 7 CHARLES A. GREEN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

C. F. PEASEE COMPANY, A CORPORATION OF DELAWARE DRAWING BOARD ATTACHMENT Application filed April 9, 1927. Serial No. 182,454.

for insuring parallel movement of the ruler or straight edge back and forth over the drawing board, but various objections to them have developed in practice. In one form of commercial device, the parallel movement is effected by a cord or cords attached parallel movement. For example, the cord to the ends of the ruler and passing around pulleys and from one side'of the drawing board to the other. Some of these cords stretch more than others in use, thereby de 0 stroying the parallel arrangement.

In the case of some devices, the ruler is longer than the board and projects considerably beyond both ends to enable said ends to be attached to the device for insuring actuated arrangement referred to embodies this feature. With this arrangement any one walking past the sides of the drawing board on which a draftsman is working is likely to brush against the projecting end of the'ruler and cause disfigurement of the drawing, especially if the same is being inked at the time. 1 1 I In other cases, the ruler is connected to a shaft which extends across the top of the drawing board and is secured to chains at its ends, or said shaft may carry pinions which run or racks mounted on each side of the drawingboard, In the first instance the shaft above the drawing board forms an obstruction, and in the second instance, the Wood warps in time so that the pinions either bind in the racks or are lifted a little, and thereby provide too much clearance or back- 5 lash, both of which are objectionable.

The object of the present invention is to obviate these difficulties and inconveniences by providing means for insuring parallel movement of the ruler, without requiring 0 the latter to project materially beyond the sides of the drawing board, the mechanism itself being located beneath said board and connected to the ends of the ruler by small inconspicuous clamping members which pass around opposite sides of the board very close thereto, with only a slight clearance to prevent friction, whereby the danger of accidentally moving one end or the other of said ruler is greatly minimized.

A further object is to provide an arrangement of this character by which the movement is positive and accurate so that the ruler always remains exactly parallel to any of its other positions on the drawing board, and whereby the movement thereof may be effected equally well, whether the ruler is grasped at one end or the other, or in the middle.

An additional object is to provide means whereby the ruler may be readily removed from its clamping members to permit it to be cleaned, particularly on the underside thereof.

In the accompanying drawings, I have illustrated one embodiment of the invention which will serve to illustrate its advantages. Other embodiments, however, are contem plated.

Figure 1 is a plan view of part of a drawing board.

Fig. 2 is a bottom view thereof.

Fig. 3 is a side view thereof.

Fig. at is a section on line 4-4, Fig. 2.

Fig. 5 is a plan of one end of the ruler and. clamping member on a larger scale.

Fig. 6 is a perspective view thereof.

Fig. 7 is a further perspective view, with the parts disconnected.

Fig. 8 is an enlarged sectional elevation through one end of the ruler and drawing board.

Fig. 9 is an enlarged side elevation of a chain tensioning device, and

Fig. 10 is an enlarged fragmentary view of one of the sprocket wheels and associated parts.

The drawing board 10 may be of any suitable material, and is shown as of the conventional rectangular outline. It is supported on a suitable standard which may comprise a pair of metal uprights 11 pivoted to the under part. of the drawing board, at 12, and provided with an adjustable clamping device 13, whereby the drawing board may be inclined or swung to nearly vertical position I when not in use I 1 A ruler 14, or straight edge, extends across the drawing board approximately from one side to the other. It is desirable that it should not project materially beyond the sides of the drawing board,-and it is preferably somewhat shorter than the length of said drawing board, from side to side, as shown in Fig. 1'. Its opposite edges may be formed of celluloid strips 15, as is usual in such cases,

A p ural ty o rackets 16 are moun d o the unders de of the drawing board and supp rt a ota ab e het 7 having a sp ocket wheel 18 at each end thereof." Two endless chains 19 pass over these sprocket wheels and also pass over second sprocket Wheels 20, supported on similar brackets, the two chains being substantially parallel and arranged eneath the drawing heard not far from h opposite sides thereof, The rotatable shaft 17 is preferably mounted near the rear edge ofthe drawing boa d; t at is, the one arthes removed from the draftsman, so as to avoid any ob r tion at the. front edge or accide ta c ntact which ight rotate the shaft The ends of the ruler are connected with the chains by two brackets 21 of generally ll-shaped o mcomposed of two angle memthroughslots 27 and be engagedby orna mental metal nuts 28.. j .7 V The'upper leg of theU-shaped member is thus adj ustably secured-to the ruler to adapt the cleviceto rulers of different lengthsgan l theupper and lowerle s areadjustahly' con nected to adapt the device to drawing boards of different thicknesses, the bottom leg carrying a knurled clamping nut29 which passes through oneof the links of thechain lland thus secures the ruler to said chain to cause the former. to move with the latter.

A further functionof the bolts 26 and 'nuts 28 is to permit ready removal of the ruler whereby the latter'may be c1eanedj,-p,ar-

ticularlythe under surface thereof which slides over the drawing paper; Y

With the arrangement described, it will be seen when the ruler is moved from front-to rear acrossthe. drawing board, or vice versa,

the chains are caused to travel ontheirsupporting sprocket wheels, and two of said wheels being directly connected by a transverse shaft, the two ends of said ruler will travel the same amount. In other words, the ruler in any position is always parallel to any of its other positions, and it maybe moved from one positionto the other byjgrasping it at any point throughout its length without disturbing this parallel arrangement; that is to say its movement will be just as accurate if grasped atone end as if it were grasped at the other end or in the middle, 7

In order to take up anyinitial slack in the chain, or in order 7 to maintain said chain tight in use under varying temperature conditions, a tightening device (Fig. is employed, consisting of a U-shaped piece of metal having a small bolt 31 securedto it and V passing through one of the links of the chain to cause an offset in thellatter'and thustight One of these de-L enit any desired degree. vices is preferably secured to each chain and at a point in the span corresponding to the bracket, connected to the opposite, span, as shown in Fig, 4, so that the said tightening device will. not interfere with thejfree move? ment of the ruler all the way across the drawing board. i V I ,7

It will also be seen that the U-shaped brackets at the ends of the ruler fit fairly closely ever the sides of the drawing board, allowing only a small clearance, sufficient to a oid actual Contact, a d, he ce, fr ct on. n other words, they project the minimum amount and therefore there is little danger of their catching in the clothing of the persons walking pas the drawing b a l,- F r er more, the chains being made of metal depot stretch with continued use as wherecordsare used, nd any var a on n the gt 'o said chains, due to temperature variations take place uniformly in both chains so that the parallelarrangement is notdistur bed, particulajrly if anyslack is taken up by means of the e i e de i ed. J j

When the attachment is 'ae eln le nitial y h drawing b0artlfit is' desirable te ads just one chain withreference to thelether so as to bring th r r parall l t nej fft'h dg s. th drawing boa-rd, for example, the front. edge. For this 'purposeone or blothot the sprocket wheels 18 on the shaft 17, as shown in Eigpli), have hubs 32 carrying setscrews 33, where y i i spro k t Wheeli ayrotated about theshaftl? and .cla nipe'd in 3.;..

any desired positio to ins e the necessary parallel arra gement.

"The equipment describe ay? be. sold eith er in the form f an attachment-t apply to a awing' board already in use, orit may 7 be mounted thereoninitially as par of't The arrangement of standard equipment. ehains-andshaft is such asto pr fvide f r movement of the ruler back; and. forth f m front tel-rear of the drawing; board in the manner customarily desired, although obviously the various parts may be otherwise mounted to provide for a parallel movement back and forth from one side of the draw ing board to the other, if desired. Various other changes may be made in the parts. described, which are referred to in detail merely to illustrate a commercial embodiment of the invention.

' What I claim as new is:

1. The combination with a drawing board, of a ruler extending substantially from one edge to the other thereof, a shaft mounted beneath said board and terminating short of said edges, a pair of sprocket wheels one on each end, secured to said shaft, a second pair of sprocket wheels mounted beneath said board with their axes of rotation parallel to said shaft and each alined with one of said first mentioned sprocket wheels, a chain passing over each pair of alined sprocket wheels, and means engaging the ends of said ruler inwardly of the adjacent edges of said board and extending around said edges into engagement with said chains for causing movement of said ruler on said drawing board to positions which are always parallel to each other.

2. The combination with a drawing board, of a ruler extending nearly across the same I but terminating short of the opposite edges thereof, means secured to the ends of said ruler extending around the edges of said drawing board and beneath the same, with only a slight clearance so as to project beyond 1 said drawing board a minimum amount, and

means beneath said drawing board secured to said first means for insuring parallel movement of said ruler. Y

3. The combination with a drawing board, of a ruler extending substantially from one edge to the other thereof, and adjustable brackets secured to the ends of said ruler extending around the edges of said drawing board, and terminating beneath the same,

with only a slight clearance at said edges.

l. The combination with a drawing board, of a ruler extending nearly across the same but terminating short of the opposite edges thereof, means secured tothe ends of said ruler extending around the edges of said drawing board and beneath the same, with only a slight clearance so as to project beyond said drawing board a minimum amount, and means beneath said drawing board secured to said first means for insuring parallel movement of said ruler, said first means being adjustable horizontally and vertically to provide for rulers ofvdiflerent lengths and for drawing boards of different thicknesses.

5. The combination with a drawing board having a ruler arranged thereon parallel to the front and rear edges thereof, of a twopart adjustable bracket secured to each end of said ruler and extending over the edges of said drawing board and beneath the same,

a chain beneath each edge of said drawing board to which said brackets are secured, sprocket Wheels supporting each chain, and means connecting said sprocket wheels for insuring equal movement of said chains to maintain said ruler parallel to said front and rear edges in any position to which it may be moved.

6. In a device of the class described, a ruler, a two-part bracket for each end thereof forminga U-shaped structure, the upper leg of said U-structure having slots therein, means secured to said ruler and passing through said slots to adjustably clamp the bracket to the ruler, the two parts of the base of said U-structure overlapping each other, one of said parts being slotted and receiving a clamping device secured to the other part, whereby the distance between the upper and lower legs may be varied, and means on said bottom leg for engaging a device beneath said drawing board for insuring the same movement of opposite ends of said ruler.

7 In a device of the class described, a drawing board, a ruler extending substantially across the same, two pairs of alined sprocket wheels secured beneath said drawing board and between the planes of the edges of said drawing board, an endless chain passing over each pair of sprocket wheels and substantially parallel to the opposite edges of said board, and a thin flat member extending from each chain around one of said edges and removably secured to an end of said ruler.

8. The combination with a drawing board of a ruler movable over the upper surface thereof, a pair of brackets, each having a flat inwardly extending portion secured to a face of said ruler, and an intermediate portion extending downwardly adjacent the edge of said board and having its lower end projecting inwardly beneath said board, and means beneath said board to which said lower ends of said brackets are secured for holding said ruler in positions of parallelism as it is moved over said board.

In testimony whereof, I have subscribed my name.

CHARLES A. GREEN. 

